#include "my_stdio.h"
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>

mFILE *mfopen(const char *filename, const char *mode)
{
	int fd = -1;
	if(strcmp(mode,"r") == 0)
	{
		fd = open(filename,O_RDONLY);
	}
	else if(strcmp(mode,"w") == 0)
	{
		fd = open(filename,O_CREAT|O_WRONLY|O_TRUNC,0666);
	}
	else if(strcmp(mode,"a") == 0)
	{
		fd = open(filename,O_CREAT|O_WRONLY|O_APPEND,0666);
	}

	if(fd < 0)
	{
		return NULL;
	}

	mFILE* mf = (mFILE*)malloc(sizeof(mFILE));
	if(!mf)
	{
		close(fd);
		return NULL;
	}
	mf->fileno = fd;
	mf->flag = FLUSH_LINE;
	mf->size = 0;
	mf->cap = SIZE;
	return mf;
}

int mfwrite(const void *ptr, int num, mFILE *stream)
{
	//1.拷贝
	memcpy(stream->outbuffer+stream->size,ptr,num);
	stream->size += num;
	//2.检测是否要刷新
	if(stream->flag == FLUSH_LINE && stream->size > 0 && stream->outbuffer[stream->size-1] == '\n')
	{
		mfflush(stream);
	}
	return num;
}

void mfflush(mFILE *stream)
{
	if(stream->size > 0)
	{
		//写到内核文件的文件缓冲区中!
		write(stream->fileno,stream->outbuffer,stream->size);
		//刷新到外设
		fsync(stream->fileno);
		stream->size = 0;
	}
}

void mfclose(mFILE *stream)
{
	if(stream->size > 0)
	{
		mfflush(stream);
	}
	close(stream->fileno);
}
